Hydrazine-free chemical bath deposition of WSe2 thin films and bi-layers for photovoltaic applications

We report the photovoltaic performance of a diode based on a p-type tungsten diselenide (WSe 2 ) active region. The device is formed by WSe 2 and cadmium sulfide (CdS) layers, both obtained via chemical bath deposition. A novel hydrazine-free chemical formulation allows deposition of WSe 2 on glass and flexible Hastelloy substrates. Characterization of WSe 2 via Raman spectroscopy shows four bands at 189, 244, 293, and 588 cm −1 . The strongest band at 293 cm −1 is assigned to the interlayer interaction mode of the WSe 2 layers. The photoluminescent characterization of Hastelloy/CdS/WSe 2 samples exhibits two excitonic transitions at 1.7860 and 1.7899 eV. The current density-voltage (J-V) measurements of the CdS/WSe 2 structure show a photovoltaic response with V OC = 180 mV, J SC = 0.07 mA cm −2 , and FF = 0.22.